1. Field of the Invention
The present invention relates to container forming machines, and in particular to a new and improved method and apparatus for forming and attaching lids to fiberboard containers.
2. Description of the Prior Art
In the packaging industry, numerous fiberboard containers and designs have been developed over the years. Such containers are typically constructed of a corrugated material and are used to ship and store a wide variety of products such as fresh fruits and vegetables, canned and bottled goods, meat, and the like. The fiberboard materials may be single face corrugated, single wall (double-faced) corrugated, double wall corrugated, triple wall corrugated, etc. Containers may also be made of other paperboard products including, without limitation, container board, boxboard, linerboard, and cardboard.
Of the numerous types of fiberboard containers that have been developed, many employ lids that are separate from the main box of the container. A "box" (or "case") is a large, usually rectangular container made out of fiberboard or paperboard and designed to hold a given number (e.g. 12 or 24) of smaller units such as cartons, bottles, cans, or produce pieces. A "tray" is a term used to describe a variety of different containers, but which is typically used to describe a style of box which uses a separate lid. Tray boxes may also refer to containers designed to hold a certain weight or volume of product (e.g. 35 pounds of grapes, 60 pounds of beef, etc.).
There are numerous machines in the industry which are used to form open ended (i.e. lidless) tray boxes. Such machines are typically included as part of a larger production line as follows: a first machine forms the empty tray box itself, a second machine fills the box with its contents, a third machine forms or provides a lid for the box, and a fourth machine attaches the lid to the box.
Existing lid forming and attaching machines are slow in operation and mechanically cumbersome. Some existing machines lift the tray box vertically up to the lid on a table which moves up and down from a lower to an upper position. The operation of such machines is extremely slow since the next box in line must wait for the table to retract to its lower position before such a box can be moved into position onto the table.
Other lid forming machines employ a ram which lowers the lid down onto the box. These machines suffer from the serious drawback of not obtaining good adhesion between the sides of the lid and the box. This is because there may be little or no lateral support for the sides of the box as the edges of the lid are pressed against it.